The field of the present invention is generally related to integrated circuits and, more particularly, to a field-testable integrated circuit having a plurality of analog signal channels with built-in test circuits, and to a method for field-testing such integrated circuit.
Generally, in situ testing of integrated circuit devices is desirable since such testing would allow for performing diagnostics in any field or site where these devices are deployed. However, as integrated circuits become ever more densely fabricated on any given semiconductor chip, the ability to monitor the performance and integrity of these integrated circuits using conventional testing techniques has become increasingly difficult. It is also desirable to provide a test circuit which uses relatively few circuit components so that the test circuit does not occupy a substantial portion of the total area of the chip where the integrated circuit is fabricated since the more chip area is allocated to the test circuit, the less chip area which remains for performing the normal functions provided by the chip. This allows for avoiding any substantial increases in the size of the chip area since the size of the chip area is directly related to the cost of the chip. Further, prior testing techniques typically limit the operational capability of the device undergoing testing since during testing the device is generally placed "off-line", thus interrupting any of the normal functions provided by the device and adding to the operational costs of the device. In general, the user has no means for performing preventative diagnostics in the field until a "hard failure" occurs and all operational capability is lost. Thus it is desirable to provide a field-testable integrated circuit which provides substantial operational capability even while undergoing testing.